The present invention relates to gas ovens, and more particularly to a built-in gas oven and an exhaust duct cooling system therefore.
Gas ovens are heated by the combustion of natural gas within the cooking chamber and in order for such combustion to occur and continue, air must be continuously supplied to the heating chamber and exhausted therefrom. In the case of a built-in gas oven, because of the surrounding cabinetry, generally the exhaust gases are ducted to the front of the oven unit and are caused to exit therefrom into the room or are directly vented to a location outside of the room or outside of the building. Front venting is preferred as it is less expensive to install, however, because of the high temperature of the combustion gases, generally it is required to insulate the exhaust duct work both from the electrical components of the oven controls as well as from the surrounding cabinetry. Exhaust temperatures are normally as high as internal oven surface temperatures and can cause problems of excessively high oven surface temperatures and fire potential on wood cabinet surfaces in proximity of the exhaust.
U.S. Pat. No. 3,485,229 to Gilliom discloses a built-in oven having ducting which draws cool air from the lower front of the oven, circulates it over the oven cavity and through a motor-fan located rearwardly above the oven cavity. Fan exhaust air is then directed horizontally over a horizontal oven exhaust duct, then over the oven controls and out vents located on the upper right front of the oven. Oven exhaust air is vented through vents located on the upper left front of the oven. No provision is made for mixing relatively cool air with oven exhaust air at the front of the oven, nor is the horizontal oven exhaust duct physically separated from the oven control area by a cool air duct.
U.S. Pat. No. 3,882,843 to Barnett, discloses a built-in oven which draws cool air through gaps on all four exterior sides of the oven cabinet. A motor-fan located in the lower rear of the oven cabinet propels the cool air around the exterior sides of the oven cavity, and over an intermediate passage which overlies the oven cavity. This cooling air is then exhausted through gaps located at the top and sides of the oven.
A horizontal intermediate passage located between an upper control chamber and the oven cavity provides a portion of the cool intake air for circulation around the oven cavity. This intermediate passage overlies a horizontal oven exhaust duct and provides a buffer of cool air between the oven control chamber and the oven exhaust duct.
Although this oven provides the feature of physically separating a horizontal oven exhaust duct from the oven control area by a cool air duct, no provision is made for mixing cooling air with hot oven exhaust air at the front of the oven, nor is this feature suggested.
U.S. Pat. No. 4,375,213 to Kemp, et al., discloses a built-in oven having ducting which draws cool air from an air intake in the lower front of the oven. One or more blowers located in a lower air chamber propel the cool air into a vertical duct located in the rear of the oven, which directs the cool air above and below a horizontal air baffle located between the oven cavity and the oven control area. Cooling air is then exhausted through openings in the front of the oven cabinet above and beneath the oven control panel.
The horizontal air baffle also overlies a horizontal oven exhaust duct which exhausts hot gases from the oven cavity. By providing ducted flow of cooling air over the oven exhaust duct, the horizontal air baffle effectively provides a buffer of cool air between the oven exhaust duct and the oven control area. A critical difference, however, is the fact that the control area is located above the cooling air duct in this oven design, not below the cooling duct. Accordingly, natural convection within the oven may cause excessive heating of the oven controls.
Further, the cooling air exhaust openings in Kemp, et al. overlies the hot oven exhaust duct openings, whereby the hot oven exhaust is mixed with and cooled by the cooling air after it is emitted from the front of the oven cabinet. The mixing occurs exteriorly of the oven and the mixed exhaust air is emitted directly at the user. Additionally, the oven exhaust opening and the cool air exhaust openings are not coextensive for the entire width of the oven, which reduces the effectiveness of the air mixing. Further, since the mixed exhaust air is emitted beneath the control panel, the heated mixed air may rise by convection to create unacceptably high temperatures on the control panel faceplate and knobs.